Occupant classification apparatus

Abstract

An occupant classification apparatus configured for classifying an occupant seated in a seat based on capacitance of and the amount of moisture contained in the occupant is disclosed. The occupant classification apparatus includes an electrode device for detecting an occupant seated in a seat, an occupant property measurement device for measuring capacitance of and the amount of moisture contained in the occupant detected by the electrode device, and a controller configured for estimating the occupant based on the capacitance and the amount of moisture measured by the occupant property measurement device.

What is claimed is: 
     
       1. An occupant classification apparatus comprising:
 an electrode device for detecting an occupant seated in a seat; 
 an occupant property measurement apparatus for measuring capacitance of and an amount of moisture contained in the occupant detected by the electrode device; and 
 a controller configured for estimating the occupant based on the capacitance and the amount of moisture measured by the occupant property measurement apparatus, 
 wherein the occupant property measurement apparatus includes:
 a discharge response signal generator for generating a discharge response signal corresponding to an amount of charge stored according to the capacitance of the occupant detected by the electrode device; 
 a capacitance determination circuit for generating a signal configured for estimating the capacitance of the occupant from the discharge response signal; and 
 a moisture detector for detecting the amount of moisture contained in the occupant according to change in electrical resistance of the occupant detected by the electrode device, and 
 
 wherein the discharge response signal generator applies a direct current (DC) power supply voltage to the electrode device to store charge according to the capacitance of the occupant detected by the electrode device and discharges the charge stored according to the capacitance of the occupant to generate the discharge response signal corresponding to the amount of charge stored according to the capacitance of the occupant. 
 
     
     
       2. The occupant classification apparatus according to  claim 1 , wherein the electrode device includes first and second electrodes mounted to overlap each other and configured to receive the DC power supply voltage and to generate an electric field. 
     
     
       3. The occupant classification apparatus according to  claim 2 , wherein the first electrode is placed adjacent to a predetermined area, in which the occupant is seated, of the seat, the second electrode is placed at an opposite side thereof, and a first-electrode-direction electric field generated by the second electrode blocks a second-electrode-direction electric field generated by the first electrode. 
     
     
       4. The occupant classification apparatus according to  claim 1 , wherein the discharge response signal generator includes:
 a power supply for providing the DC power supply voltage to the electrode device; 
 a detection capacitor; and 
 a switch for selectively determining an electrical connection between the electrode device and the power supply and an electrical connection between the electrode device and the detection capacitor, 
 wherein, when the switch establishes the electrical connection between the electrode device and the detection capacitor, a power supply voltage is applied to the detection capacitor during a predetermined time period, and a voltage of the detection capacitor is the discharge response signal. 
 
     
     
       5. The occupant classification apparatus according to  claim 4 , wherein the controller is configured to control the switch to establish the electrical connection between the electrode device and the detection capacitor in a state of establishing the electrical connection between the electrode device and the power supply to perform charging by the capacitance of the occupant detected by the electrode device, wherein the charge stored according to the capacitance of the occupant detected by the electrode device is discharged, the discharged charge is provided to the detection capacitor to form an initial voltage of the detection capacitor, and the detection capacitor is charged by the power supply voltage provided during the predetermined time period after forming the initial voltage. 
     
     
       6. The occupant classification apparatus according to  claim 5 , wherein the capacitance determination circuit outputs the generated signal including change in the voltage of the detection capacitor increasing from the initial voltage as the generated signal configured for estimating the capacitance. 
     
     
       7. The occupant classification apparatus according to  claim 6 , wherein the capacitor determination circuit includes:
 a reference signal generator for generating a reference signal having a logic high value in a period in which the voltage of the detection capacitor increases from the initial voltage and having a logic low value before the voltage of the detection capacitor decreases to a predetermined reference voltage or less after increasing the voltage of the detection capacitor; and 
 a NAND logic element for receiving the voltage of the detection capacitor and the reference signal and outputting a result of performing a NAND logic operation with respect to the voltage of the detection capacitor and the reference signal. 
 
     
     
       8. The occupant classification apparatus according to  claim 1 , wherein the moisture detector detects change in current according to change in electrical resistance of the occupant detected by the electrode device in a state of applying the DC power supply voltage to the electrode device to detect the amount of moisture contained in the occupant. 
     
     
       9. The occupant classification apparatus according to  claim 1 , wherein the controller includes predetermined ranges associated with the capacitance of the occupant and the amount of moisture contained in the occupant according to a type of the occupant and is configured to determine a predetermined range, to which the capacitance of the occupant and the amount of moisture measured by the occupant property measurement apparatus belong, to determine the type of the occupant seated in the seat. 
     
     
       10. An occupant classification apparatus comprising:
 an electrode device for receiving a direct current (DC) power supply voltage, wherein an electric field is formed in a measurement area, in which an occupant is located, to sense the occupant seated in a seat; 
 an occupant property measurement apparatus for providing the DC power supply voltage to the electrode device, generating a first signal corresponding to a capacitance of the occupant based on another signal generated by discharging charge stored according to the capacitance of the occupant in the measurement area and generating a second signal corresponding to an amount of moisture contained in the occupant based on change in electrical resistance of the occupant detected in the measurement area; and 
 a controller configured for estimating the occupant based on the first signal corresponding to the capacitance of the occupant and the second signal corresponding to the amount of moisture contained in the occupant, 
 wherein the occupant property measurement apparatus:
 selectively and electrically connects the electrode device to the DC power supply voltage and a detection capacitor under control of the controller, and 
 performs charging by the capacitance of the occupant detected in the measurement area, when an electrical connection between the electrode device and the DC power supply voltage is established, and discharges the charge stored according to the capacitance of the occupant detected in the measurement area, provides the discharged charge to the detection capacitor to form an initial voltage of the detection capacitor and charges the detection capacitor by the DC power supply voltage during a predetermined time period after forming the initial voltage of the detection capacitor, when an electrical connection between the electrode device and the detection capacitor is established. 
 
 
     
     
       11. The occupant classification apparatus according to  claim 10 , wherein the occupant property measurement apparatus outputs information based on a time required for a voltage of the detection capacitor to increase from the initial voltage of the detection capacitor to a predetermined reference voltage as the first signal corresponding to the capacitance of the occupant.